HOUTMAN’S ABROLHOS. 143 
actually in sight, and the boats may indeed disappear from view again before they 
come within the range of ordinary vision. On the reefs of the Great Barrier 
system, on the Queensland coast, the phenomenon of mirage exemplified by the 
abnormal elevation of the breaking waves may be very generally observed, the detached 
rock-masses, lying on the outer margins, black through exposure of the weather, and 
popularly known as “nigger-heads,” standing out in marked contrast to the snowy 
whiteness of the breakers. In the neighbourhood of Torres Straits and the Warrior 
Reefs, white pelicans commonly take up their station on these reefs at low tide, 
and, approached under conditions favourable to the manifestation of mirage phe- 
nomena, seem to stand high in the air and to be of colossal size. 
An additional illustration of the aspect of the mirage-elevated breakers on the 
Pelsart barrier is afforded by the photograph reproduced at the foot of page 132. 
In this photograph, which was taken with the camera erected on a partly submerged 
rocky ledge within the lagoon, several distinctive features are clearly defined. While 
the breakers extend throughout the entire length of the horizon, the middle distance 
is occupied by the level platform reef, upon which are resting several huge masses of 
rock that have been torn off the outer margin of the reef and hurled to their present 
position during a storm of unusual violence. On the rock-mass to the left, one of 
the shore-birds popularly called Red-bills, Hamatopus, is distinctly visible, and in the 
original negative there are others also on the farther rocks. A very characteristic 
photograph of similar storm-stranded coral-rock. masses, taken at close quarters on 
the Capricorn Island reefs, on the Queensland coast, is furnished by Plate XXX. of 
the author’s recently published work “The Great Barrier Reef of Australia.” A near 
approach to the masses on the Abrolhos barrier was not practicable during the seasons 
of the author's visits. The water, even at lowest tide, was continually surging over 
from the outer ocean, and though a foothold for a brief interval with the water 
knee-deep might be retained, a succeeding wave would bring a flood against 
which it was impossible to stand, much more to effectually erect and work the 
camera. In the photograph here reproduced, one exhausted wave is delivering its 
spent energies into the lagoon, while a second one overflowing from the outer waters 
has advanced about half-way across the platform reef. 
With reference to the violet-tinted branching Madrepora that enters so exten- 
sively into the composition of the Coloured Reef View illustrated by Chromo-Plate IV., 
it may be mentioned that in the deeper and stiller areas of Pelsart Island lagoon, 
with the water from five to ten fathoms deep, masses of this same Madrepora cover 
